Liquid level controller employing vortex valve



United States Patent [72] Inventors Peter A. Freeman Baltimore; RobertA. Bean, Rockville, Maryland [21] AppLNo. 822,272 [22] Filed May 6,1969[45] Patented Dec. 8, 1970 [73] Assignee Bowles Engineering CorporationSilver Spring, Maryland a corporation of Maryland [54] LIQUID LEVELCONTROLLER EMPLOYING VORTEXVALVE 8 Claims, 4 Drawing Figs.

[52] U.S.Cl 137/815 [51] Int.Cl Fl5cl/16 [50] Fieldot'Search 137/815,393

[ 56] References Cited UNITED STATES PATENTS 3,195,303 7/1965 Widell137/81.5X 3,267,946 8/1966 Adamsetal. 137/81.5 3,276,259 10/1966Bowlesetal 137/81.5X 3,392,741 7/1968 Shinn 137/815 3,410,187 11/1968Heydenetal. 137/81.5X 3,417,772 12/1968 Schaeffer 137/815 3,463,1788/1969 Kirchmier 137/815 3,467,122 9/1969 Jones ABSTRACT: Liquid levelcontrol in a boiler other pressurized liquid container is achieved witha vortex valve. Outflow from the container is split between supply andbias inlets at the periphery of the vortex valve chamber, the supplyflow issuing radially into the chamber and the bias flow issuingtangentially into the chamber. A sensor tube has its sensing enddisposed at a predetermined level in the tank and is connected to acontrol inlet at the chamber periphery from which control flow issuestangentially into the chamber in opposition to the bias flow. Liquidabove the predetermined level flows through the control inlet withsufficient momentum to balance the bias flow, causing the supply, biasand control flows to flow radially and unimpeded to an axial outletpassage. When the liquid is below the predetermined level, vapor in thecontainer flows through the control inlet with insufficient momentum toovercome the bias flow which deflects the supply flow into a throttledvortical flow path to the outlet passage.

Liquid level is similarly achieved in an unpressurized liquid container,the vortex valve chamber being disposed lower than said. predeterminedlevel and the sensor tube being oriented to permit liquid above saidpredetermined level to flow from the tank to the control inlet of thevalve.

- lNFLOLU PATENTEU DEC 8|97D 3 545 168 PETER A. FREEMAN 81 ROBERT A.BEAN ATTORNEYS EINVENTIORS I LIQUID LEVEL CONTROLLER EMPLOYING VORTEXVALVE BACKGROUND OF THE INVENTION The present invention relates tofluidic liquid level controllers, and more particularly to suchcontrollers which selectively vary the outflow from a liquid containerin order to maintain the liquid at or below a predetermined level.

Level detection and control by means of fluidic components is known inthe prior art, as witnessed by U.S. Pat. Nos. 3,267,949 and3,277,l94.The advantages of fluidics over mechanical valves forperforming these functions include the absence of mechanical movingparts from fluidic elements; more specifically, mechanical valves tendto stick or otherwise fail, thereby providing unreliable level detectionand control.

Heretofore, fluidic level detection and control functions have beenemployed with filling operations whereby the inflow of liquid into acontainer is controlled by the liquid level in the container. In somelevel control applications however, it is more practical to control thecontainer outflow in accordance with container liquid level. This isparticularly true in the case of closed pressurized containers such asboilers, from which the outflow is employed to perform a specifiedfunction. At present,level controlled outflow functions are performed bymechanical valves.

It is therefore an object of the present invention to provide a fluidicliquid level detection and control apparatus for controlling the outflowof liquid from a container.

It is another object of the present invention to provide j a fluidicapparatus for controlling the outflow of liquid from a pressurizedcontainer in accordance with the level of liquid in the container.

SUMMARY or THE INVENTION In accordance, with the principles of thepresent invention, outflow from a pressurized container is passedthrough a vortex valve which is selectively throttled as a function ofthe liquid level in the container. The outflow is split into a supplyflow directed radially across the valve and a bias flow directedtangentially into the valve. Control isachieved with a sensor tubehaving an inlet at the desired liquid height in the container and anoutlet oriented to issue control flow tangentially into the valve inopposition to the bias flow. The sensor. tube issues liquid into thevalve when the liquid level is higher than desired and issues vapor intothe valve when the liquid level is lower than desired. When the controlflow is liquid, the effect of the bias flow is balanced and the supply,-bias and control flows are directed radially and without substantialimpedance across the valve. When the control flow is vapor, the latteris insufficient to overcome the bias flow which deflects the supply flowinto a vortical flow pattern across the valve chamber. When a vortex isinduced in the valve chamber, a pressure gradient is created across thechamber causing a high-pressure downstream of the supply inlet and anincreased impedance to flow through the vortex valve. Valve outflow isthus controlled by the liquid level in the tank.

In another aspect of the present invention, the liquid container neednot be pressurized in order to achieve the level detection and controldescribed above. In this case the sensor tube is arranged to flowcontrol fluid to the vortex valve by gravity feed to oppose the biasflow whenever the level in the container is above the desired level.

BRIEF DESCRIPTION OF THE DRAWINGS .the accompanying drawings, wherein:

FIG. I is a schematic illustration of a preferred embodiment of thepresent invention;

FIGS. 2 and 3 are respective diagrammatic illustrations of respectiveoperating modes of a vortex valve employed in the present invention; and

FIG. 4 is a schematic illustration of an alternate embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1 of theaccompanying drawings there is illustrated a closed container or tank 11containing liquid and vapor under pressure. For example, tank 11 mayrepresent a boiler. Liquid inflow means 13 are provided for supplyingliquid to the tankand an outflow passage 15 is provided to conductliquid outflow from the tank. The liquid level detection and controlarrangement of the present invention is intended to maintain the liquidin tank 11 at a specified level A-A' in spite of inflow variationsgreater or less than some nominal inflow.

A vortex valve 17 comprises a cylindrical chamber having an axial outletpassage 19, a supply inlet port 21, a bias inlet port 23 and a controlinlet port 25. Supply inlet port 21 is arranged to issue pressurizedfluid received thereby radially across the cylindrical chamber to outletpassage 19. Bias port 23 and control port 25 are disposed to issue fluidreceived thereby in substantial opposition and tangential to the valvechamber. In the particular embodiment illustrated in FIG. I, controlport 25 and bias port 23 are arranged in substantial opposition onopposite sides of supply port 21; however, this configuration is by wayof example only since the control and bias ports may be otherwisedisposed as long as their resulting outflows aretangentially issued intothe valve chamber and in opposite directions to one another.

Outflow from tank-11 via passage 15 is applied directly to supply port21 and is also applied through an adjustable pressure dropping flowrestrictor 27 to bias port 23. A sensor tube 29 has its inlet enddisposed in tank 11 at level A-A' and its downstream end connected tocontrol port 25.

In operation, when the liquid in tank 1 1 is above level AA', liquidflows through sensor tube 29 to control port 25 and issues tangentiallyinto the chamber of valve 17. Adjustable flow restrictor 27 is adjustedso that the outflow from tank 11 flowing to bias port 23 just balancesthe liquid control flow through control port 25. The resulting flowpattern is illustrated in FIG. 2 wherein the bias, supply, and controlflows merge and flow radially across the valve chamber and out throughoutlet passage 19. There is minimal impedance to flow in this mode andtherefore the outflow from tank 11 is maximum. Note thatin addition tothe low impedance to supply flow in this mode, there is substantialadditional liquid outflow from tank 11 in the form of control flowthrough sensor tube 29 and control port 25 When the liquid inpressurizedtank 11 is below level A-A', there is no liquid flow throughsensor tube 29, rather, vapor, present above the liquid in tank 11,flows through sensor tube 29 to control port 25. In a typical case of aboiler, control port 25 can be adjusted to pass twenty-five times themass flow of saturated water as saturated steam. The number twenty-fivedepends upon the specific operating pressure and type of liquid in theboiler; it is not a unique number which would limit the invention.Similarly large ratios of liquid-to-vapor mass flows are achieved withother liquids, the control port being sized to provide a maximum liquidflow without providing a vapor flow that effectively opposes the thebias flow. Consequently, the flow pattern in the chamber of valve 17 isvortical as illustrated in FIG. 3. More specifically, the vapor flowingthrough sensor tube 29 condenses upon contact with the supply flow,allowing the bias flow to predominate and create a vortical flowpattern. As is well known, when a vortex is induced in the valvechamber, a pressure gradient is created across the chamber causing ahigh pressure at the perphery of the chamber and increasing theimpedance to supply flow through the chamber. Total outflow from tank 11is therefore reduced by virtue of the increased impedance. Moreover,since control port 25 is flowing vapor in this mode at about onetwenty-fifth (for example) the mass flow of liquid in the previouslydescribed mode, there is an additional reduction in tank outflow.

In actual operation when the inflow to tank 11 is steady, the liquidlevel in tank 11 limit-cycles about the inlet of sensor tube 29 causinga mixture of liquid and vapor to enter the tube. Under these conditionsa relatively weak vortex is created in the valve chamber, keeping thetank outflow at some steady intermediate level. If the inflow to thetank increases, the liquid level tries to rise, causing an increase inthe proportion of liquid in the sensor tube, lessening the vortex andallowing greater tank'outflow. Contrarily, lowering the inflow to thetank increases the proportion of vapor in tube 29 and therebystrengthens the vortex and lessens tank outflow.

Referring now to FIG. 4, an alternate embodiment of the presentinvention is employed to control the liquid level in a nonpressurizedtank 31. inflow means 33 supplies liquid to the tank and outflow isprovided through an outlet passage 35.

A vortex valve 37, similar in configuration to valve 17 of FIG. 1,includes an axial outlet passage 39, a radially directed supply inletport 41, and opposed tangentially oriented bias and control ports 43 and45 respectively. Outlet passage 35 is connected directly to supply port41 and through adjustable flow restrictor 47 to bias port 43.

A sensor tube 49 has its inlet end disposed at control level A-A' intank 31 and supplies flow to control port 45. Sensor tube 49 and valve17 are oriented so that liquid in tank 31 above level A-A' is gravityfed to control port 45. The adjustable restrictor 47 is set to balanceliquid flow through sensor tube 49.

Operation of the arrangement in FIG. 4 is similar to that for FIG. 1except for the absence of vapor flow when liquid is below level A-A' intank 31. In this mode there is no flow through control port 45 and astrong vortex is formed in valve 37 which impedes outflow from tank 31.When liquid rises above level A-A', the vortex terminates andsubstantially unimpeded radial flow, including the supply, bias, andcontrol flows, traverse the valve chamber and egress through passage 39.

While we have described and illustrated specific embodiments of ourinvention, it will be clear that variation of the details ofconstruction which are specifically illustrated and described may beresorted to without departing from the true spirit and scope of theinvention as defined in the appended claims.

We claim:

1. A fluidic apparatus for controlling the liquid level in a container,said apparatus comprising:

means for outflowing liquid from said container; a sensor tube having aninlet end disposed at a predetermined level in said container and anoutlet end; a vortex valve having a chamber of circular cross section,an outlet passage disposed axially of said chamber for conducting fluidfrom said chamber, a supply inlet port responsive to pressurized fluidapplied thereto for issuing a fluid stream radially across said chambertoward said outlet passage, and control and bias inlet ports responsiveto pressurized fluid thereto for issuing respective control and biasflows into said chamber tangentially of said circular cross section,said control flow being directed in an opposite sense to said bias flow;means for connecting said outlet end of said sensor tube to said controlport such that liquid from said container flows to said control portwhenever the liquid in said container is above said predetermined level;means for applying said outflowing liquid to said supply and bias ports;and

pressure-dropping means connected to said bias port for reducing theflow of said outflowing liquid to said bias port sufficiently to renderthe mass flow rates of said control and bias flows equal and oppositewhenever the liquid in said container is above said predetermined level.

2. The apparatus according to claim 1 wherein said container is apressurized tank and wherein vapor flows through said sensor tube tosaid control port at a substantially lower mass flow rate than said biasflow whenever the liquid in said container is below said predeterminedlevel.

3. The apparatus according to claim 1 wherem said sensor tube isarranged to gravity-feed liquid from said container to said control portwhenever liquid in said container is above said predetermined level.

4. The apparatus according to claim 1 wherein said pressure-droppingmeans comprises an adjustable flow restrictor.

5. A fluidic apparatus for controlling the outflow of liquid from apressurized tank in accordance with the level of liquid in said tank,said apparatus comprising:

a vortex valve having a chamber of circular cross section, an

outlet passage disposed axially of said circular cross section forconducting fluid out of said chamber, a supply inlet port responsive topressurized fluid applied thereto for issuing a fluid supply flow intosaid chamber radially of said circular cross section and toward saidoutlet passage, a bias inlet port responsive to pressurized fluidapplied thereto for issuing a bias flow into said chamber tangentiallyof said circular cross section and in interacting relationship with saidsupply flow such that said supply and bias flows assume a vortical flowpath along which said supply and bias flows egress from said chamberthrough said outlet passage, and a control inlet port responsive topressurized fluid applied thereto for issuing a control flow into saidchamber tangentially of said circular cross section and in an oppositesense to said bias flow;

a sensor tube having an inlet end disposed at a predetermined level insaid tank and an outlet 1 end connected to said control port for flowingpressurized liquid from said tank to said control port whenever theliquid in said tank is above said predetermined level;

means for applying liquid outflow from said tank to said supply and biasports; and

means for restricting liquid outflow to said bias port suffi ciently toprevent creation of a vortex in said chamber whenever liquid in saidtank is above said predetermined level.

6. The apparatus according to claim 5 wherein said means for restrictingcomprises an adjustable flow restrictor.

7. The apparatus according to claim 5 wherein said tank contains liquidand a vapor under pressure, and wherein said vapor flows through saidsensor tube to said control port whenever the liquid in said tank isbelow said predetermined level and liquid flows through said sensor tubeto said control port whenever liquid in said tank is above saidpredetermined level.

8. The apparatus according to claim 7 further comprising means forsupplying liquid to said tank at a steady flow rate such that the liquidin said tank limit-cycles about said predetennined level whereby acombination of vapor and liquid flows through said sensor tube to saidcontrol port to permit creation of a relatively weak steady vorticalflow pattern in said chamber.

